Do you have a bar code reader? If you do, simply open notepad and "scan" a bar code. You' ll see that the translated code is typed into notepad (just as if it was entered using an ordinary keyboard). You might need to strip the start and end character (as I have encountered myself which was the pound character '#' ) but that's all. The hard work is already done by the bar code reader itself.
Here some general information on different barcode types and fonts:
http://www.barcodingfonts.com/blog/[
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Good luck!